We will evaluate the effect of the material and fetal endocrine glands, including the placenta, on the mechanisms that control the initiation of parturition and the ontogeny of target tissues in the fetus of the rhesus monkey. The effects of the secretions of the pituitary, adrenal glands, and placenta will be our principal focus. We will also evaluate in the rhesus fetus the effects of functional hypophysectomy on organ development and the initiation of parturition and determine the biosynthetic and metabolic pathways of steroids in the fetoplacental unit of the rhesus monkey. Our main goal will be to determine how the biosynthesis and metabolism of the steroid hormones are controlled in the fetoplacental unit of primates and how these processes are affected by the fetal hypothalamic-pituitary axis.